I have done Aikido on a few ocassions in street clothes and agree its a "different feel"; less flexible and more restrictive.

It's only because its different and therefore self conscious. I was quite proud of myself the first time I was given an impromtu lesson in street clothes in a field - everything came togeather nicely. Imagine the consternation the next time the environment was different and I fell apart. The first time the person who took me out knew what he was on about, the second time the senior person (me) did not. Once I understood the difference it becomes a valuable lesson and does not have to be repeated regularly.